I can't breathe

Anna
I'm 31weeks & over the last week or so I've noticed at night (after dinner) I start to get this feeling where I can't fill my lungs to satisfaction. I can breathe, I know I'm getting oxygen, but maybe 1 in 30 breaths feel... Full? And when it's midnight & you gotta get up at 6am and you can't sleep because you "can't breathe" you start to panic. Well - I do at least. And again - I KNOW I'm getting oxygen, but it doesn't seem like enough. I'll start yawning to try and fill my lungs which sometimes helps. I read you can lay partially elevated & it will help (it didn't") or to get on your hands and knees let gravity pull your stomach & baby far enough away that your lungs have enough room to expand (it does) - But you can't sleep that way... And it's been 5 nights straight of 3-4 hours of sleep. I feel like I'm going crazy. I have a drs appt tomorrow but I feel like he is just going to use the old "this is one of those pregnancy things you just gotta deal with" but I just CANNOT IMAGINE another 2 months of this. Is anyone else experiencing this? Any other ideas? Ugh please let me get some relief. Or SLEEP. ZZZZzzzzzz